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Power to weight... again
J666AYP - 9/8/19 at 04:18 PM

Hi gents,

Just spinning some numbers in my head and trying to work out a game plan.

The project (when it's up and running) will be about 600kgs and have roughly 250-260hp until I shell out for the M90 upgrade and a decent diff. Is this going to be too heavy for a serious road car with occasional track use? Or do I need to start shaving down bolts and brackets ect to get it more towards the 550kg mark? Or..... do I just go down the easy route and just add more power?

I know lighter the better to some extent but there has to be a middle ground between weigh and power?

Any input appreciated as this will govern how I progress with the build.

Jay


CosKev3 - 9/8/19 at 04:32 PM

No that will be a stupidly fast car!

Mines now 700kg with three quarters of a tank of fuel,286bhp so that makes it 408bhp per ton.

It goes very well!

Have a look at other cars that are in the low 400bhp per ton bracket and you'll have a good idea on how it goes.

260bhp and 600kgs gives you 433bhp per ton


bi22le - 9/8/19 at 05:03 PM

433bhp/ ton is a 500bhp tintop, and that's good power.

Lighter is faster, but power can help that alot.

I have "only" 280bhp/ ton and am always comparibly quick on a track day.

Your 433 punches well above its weight on a track as your brakes only have to do half the weight.


coyoteboy - 9/8/19 at 10:53 PM

quote:
Originally posted by bi22le
433bhp/ ton is a 500bhp tintop, and that's good power.

Lighter is faster, but power can help that alot.

I have "only" 280bhp/ ton and am always comparibly quick on a track day.

Your 433 punches well above its weight on a track as your brakes only have to do half the weight.


Id say closer to a 600hp tintop, most 600hp cars are 1.3+ tons. And as you roughly say, adding power helps in the straights but losing weight helps everywhere.


fregis - 10/8/19 at 10:54 AM

My opinion dont bother about weitght so much. It is 550, 600 or 650kg, will still be low weight and to use full that power on track need skills and balls.
I sugest go for start with more weight, and later when start using full throttle go for lighter.


J666AYP - 10/8/19 at 11:58 AM

Thanks for the info gents. Think I will put off the M90 swap for now then and be a little more careful about putting any more weight into it. I'm building it up with all the supporting engine mods incase more power is ever needed.

Jay


jeffw - 10/8/19 at 12:02 PM

The less it weighs, the less you have to stop and turn.

The Phoenix was 630Kg and 400BHP and was a reasonably rapid kitcar, the Zeus is 530Kg and 550BHP-600BHP and is a completely different level.


J666AYP - 10/8/19 at 01:21 PM

quote:
Originally posted by jeffw
The less it weighs, the less you have to stop and turn.

The Phoenix was 630Kg and 400BHP and was a reasonably rapid kitcar, the Zeus is 530Kg and 550BHP-600BHP and is a completely different level.


I would be happy with the 400BHP

[Edited on 10/8/19 by J666AYP]


snapper - 10/8/19 at 03:00 PM

Depending on how much you weigh perhaps a tin or two of slim fast might make more of a difference 😆


J666AYP - 10/8/19 at 03:24 PM

quote:
Originally posted by snapper
Depending on how much you weigh perhaps a tin or two of slim fast might make more of a difference 😆


I'm 6'1" and 14 stone so I cant shed too much body weight